Ultimate bearing capacity: Maximum gross pressure that can be apply at the base of foundation without shear failure or it may also be defined as minimum gross pressure at which soil fails in shear.
Net safe bearing capacity: Net ultimate bearing capacity divided by factor of safety
Safe bearing capacity: Maximum gross pressure which soil can carry safely at the base of foundation without risk of shear failure
Allowable bearing pressure: Maximum net pressure that can be applied on the soil safely without the possibility of shear failure or settlement failure.